#include <iostream>
using std::cout;
using std::endl;

double sum()
{
    return 0;
}

template <class T, class ...Args>
double sum(T x, Args ...args)
{
    return x + sum(args...);
}

void test0(){
    double res = sum(1,4.5,6.7,8.1,9,3.9);
    cout << res << endl;
}

int main(void){
    test0();
    return 0;
}





